Pregnancy Due Date Calculator
Estimates a due date from the last menstrual period (Naegele’s rule).
Inputs
- First day of last period
Example
Estimated due date: 2026-10-08
| Estimated conception | 2026-01-15 |
|---|---|
| Due day of week | Thursday |
How it works
Naegele’s rule: last period + 280 days (40 weeks). An estimate; confirm with a doctor.
FAQ
How does the Pregnancy Due Date Calculator work?
Estimates a due date from the last menstrual period (Naegele’s rule). Naegele’s rule: last period + 280 days (40 weeks). An estimate; confirm with a doctor.
Is the Pregnancy Due Date Calculator free?
Yes — every calculator on Calcova is free and you can download the results to Excel.